The present invention relates to a device used to facilitate coupling a kingpin trailer with a tow vehicle. More particularly, this invention relates to an offset coupler for use in connecting a kingpin trailer with a fifth wheel hitch to permit the relative space between the tow vehicle and the kingpin trailer to be increased.
By virtue of the numerous advantages received over bumper pulled trailers, gooseneck trailers and kingpin trailers have received virtually universal acceptance in the towing of large trailers. Kingpin trailers are used in connection with a fifth wheel hitch mechanism. In this arrangement, the trailer generally has a downwardly depending post that terminates in a fifth wheel kingpin plate or skid plate. The plate generally has a kingpin extending downwardly therefrom. A fifth wheel hitch or fifth wheel receiver is mounted in the bed of a truck for receiving the kingpin. The receiver is similar in appearance and functions similar to the device found on the back of a semi-truck. The receiver is a generally horseshoe shaped device having a flat upper surface. The kingpin is received in the center of the horseshoe shaped receiver and the kingpin plate of the trailer rides on and pivots on the upper surface of the receiver.
The fifth wheel receiver is mounted to the floor of or in the bed of a tow vehicle, such as a pickup truck. The receiver is mounted such that the kingpin, when received in the fifth wheel receiver, is slightly ahead of the rear axle, thereby giving the kingpin trailer/fifth wheel receiver arrangement its advantage over bumper pulled trailers by transferring the weight of the trailer more evenly between the front and rear axles of the tow vehicle and, by virtue of the geometry associated therewith, permitting the load of the trailer to pass directly onto the rear axle of the truck instead of onto its bumper.
While the use of a kingpin trailer/fifth wheel receiver arrangement has numerous benefits, one drawback is found when it is employed in a short bed pickup truck. In recent years, a trend has emerged by truck manufacturers to increase the size of the interior cab space for user comfort. First introduced were stretch cab trucks followed by extended cab trucks and, even more recently, crew cab or four door trucks. While the cabs of these trucks have in essence been lengthened, the wheel base or footprint of these pickup trucks have remained largely unchanged. As a result, the beds of these trucks are respectively shortened. This arrangement permits a truck manufacturer to provide a truck with more interior space, while not sacrificing mobility and maneuverability for the trucks. It also prevents the manufacturers from having to produce longer and longer trucks which might not be as appealing to purchasers.
The new short bed trucks have created a problem with respect to kingpin trailers. The problem is a decrease in the clearance between the nose of the trailer and the rear of the cab of the tow vehicle when the kingpin trailer is coupled with the tow vehicle. Because the bed is shortened, the distance between the fifth wheel receiver and the back of the cab in a short bed truck is shorter than it would normally be in a truck with a standard length bed. Accordingly, the front of the trailer is now closer to the rear of the cab. As a result, the driver of the short bed tow vehicle cannot make as sharp of turns as a driver of a long bed tow vehicle, as discussed in greater detail below.
Another problem associated with kingpin trailers in general can be the clearance between the rear of the truck and the bulkhead of the trailer. Spare tires, propane tanks or other items are often mounted to the outside of the bulkhead of a kingpin trailer. As a result, the distance between the front of the trailer and the back of the truck is effectively shortened. Generally, when coupling a kingpin trailer to a pickup truck, the tailgate of the truck is lowered so that the truck may be backed up towards the trailer until the kingpin is received in the fifth wheel hitch receiver without risk of the kingpin hitting the tailgate. It is often the case, however, that the tailgate would make contact with the item mounted on the front of the bulkhead of the trailer before the kingpin can be received in the fifth wheel hitch. As a result, it is often necessary to back the truck partially under the trailer and then raise the tailgate back up before being permitted to back further under the trailer for coupling.
Therefore, there is a need for a device which permits the user to couple a kingpin trailer with a tow vehicle having a fifth wheel hitch in an arrangement that permits the kingpin trailer to be moved further away from the tow vehicle than permitted by present coupler devices. The present invention fills these and other needs.